He is talking about Juvie Angels...not full grown ones.
IMO, 6-8 Angels is OK to keep when they are small, but they will need a bigger tank when they are bigger. It will not be a permanent home for them. You could house 4-6 in that tank without moving IMO, but 8 is too much.
6 would be the limit, but if you end up with a breeding pair, then they will take at least half the tank.
I currently have German Blue Rams with my angels and they dont bother each other. You can also keep various small community fish. They should be fast swimmers and big enough to not fit in the Angel's mouth. You can also keep cories or loaches etc